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					Determining The Heart’s
     Electrical Axis
     Principles To Remember
 Principle# 1 : When a positive
 sensing electrode sees an electrical
 impulse as coming head on, it will
 write the highest amplitude
 deflection on the EKG paper.
          # 2 : When the positive
 Principle
 sensing electrode sees an electrical
 impulse crossing it on a
 perpendicular path, it will write
 the smallest amplitude deflection
 on the EKG paper.
          Quadrants

   the electrical axis of the
 If
 heart is between + 0 & +90
 degrees, the axis is said to be
 in the normal quadrant
   the electrical axis of the
 If
 heart is between -0 & -90
 degrees, it is said to be in left
 axis deviation
   the electrical axis of the
 If
 heart is between +90 and +180
 degrees, it is said to be in right
 axis deviation
   the electrical axis of the heart is
 If
 between -180 and -90 degrees, it is
 said to be in extreme right axis
 deviation
Now, How Do We Determine
         Axis ?


 Look   at Lead I and aVF
 Step#1 : Determine if the
 overall QRS complex
 deflection is grossly positive
 or grossly negative in Leads I
 and aVF
 Step#2 : If the QRS are both
 positively deflected, then the
 electrical axis is in the normal
 quadrant (up,up)
   the QRS complex for Lead I is
 If
 positively deflected but the QRS in
 avF is negatively deflected, then
 the electrical axis is said to be left
 axis deviated (up,down)
 Ifthe QRS complex in Lead I
 is negatively deflected but the
 QRS in aVF is positively
 deflected, then the electrical
 axis is said to be right axis
 deviated (down,up)
   the QRS in Lead I and in
 If
 aVF are both negatively
 deflected, the electrical axis is
 said to be extreme right axis
 deviated (down,down)
         Fine Tuning

 Itis not enough to merely
 determine the quadrant. It is
 better to be able to determine
 where in the quadrant the axis
 is located.
   The Tools To Fine Tune

 Determine   the quadrant
 Find the smallest QRS
  deflection in the six standard
  leads
 Rotate90 degrees from the
 smallest electrode into the
 quadrant that Lead I & aVF
 said the axis would be located.
 Determine if the QRS complex
 of the smallest deflection is
 grossly positive or negative.
 Ifthe R wave to S wave
 difference is 0-1 mm, make no
 fine adjustments in the axis
 degree setting.
   the R wave to S wave
 If
 difference is between 2-3 mm,
 then adjust the axis 10 degrees
 towards the + or - pole of the
 smallest QRS.
 Ifthe smallest QRS deflection
 is grossly negative, the fine
 adjustment of 10 degrees is
 swung toward the negative
 pole of that lead.
 Ifthe smallest QRS deflection
 is grossly positive, the fine
 adjustment of 10 degrees is
 swung toward the positive
 pole of that lead.
   the R wave to S wave
 If
 difference is between 4-5 mm,
 then adjust the axis 15 degrees
 towards the + or - pole of the
 smallest QRS.

				
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posted:8/4/2011
language:English
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